In developing the periodic table, Dmitri Mendeleev predicted the existence and properties of an undiscovered element he called eka-silicon. Which element was later discovered that matched this prediction?

• A. Germanium (Ge)
• B. Scandium (Sc)
• C. Neon (Ne)
• D. Gallium (Ga)

Answer: (A)

Verified step by step guidance

1. Understand that Dmitri Mendeleev arranged elements in the periodic table based on their atomic masses and properties, leaving gaps for undiscovered elements.
2. Recognize that Mendeleev used the prefix 'eka-' to name predicted elements based on their position relative to known elements; 'eka-silicon' refers to the element one period below silicon.
3. Identify the element directly below silicon (Si) in the periodic table, which would have similar chemical properties but a higher atomic number.
4. Recall that the element discovered later that matched Mendeleev's predictions for eka-silicon is Germanium (Ge).
5. Note that the other options (Scandium, Neon, Gallium) do not fit the position or properties predicted for eka-silicon.